Valve for pneumatic tools



. 1,636,651 July 19 1927' l w. A. SMITH, JR,

VALVE FOR PNEUMATIC TOOLS Filed Nov. 5. 1926 Patented July 19, 1927.

, UNITED STATES APA 1,636,661 TENT OFFICE.

WILLIAM A. sMITII, JR., OE NEW YORK, N. Y., AssIeNoRv TO INGERsoLL-RANDooM- EANY, OE JERSEY CITY, NEW JERsEY, A CORPORATION OE NEW JERSEY. Y

`VALVE EORINEUMAT'IC TOOLS.

Application filed November This/invention relates to pneumatic tools,but more particularly to an improved distributing valve for tools ofthis type.

The objects of the invention are to obtain a quick and positive actionof the valve and to obtain a powerful blow of the hammer piston againstthe working implement.

Other objects will'appear hereinafter and to all of these ends theinvention consists of the combination of elements, features of construction and arrangementof parts having the general mode of loperationsubstantially as hereinafter described and claimed and illustrated inthe accompanying drawings, in r which Figure l is a sectional elevationof a pneumatic tool showing' the reciprocatory elements in one or' theirlimiting positions, and

Figure 2 is a view similar to Figure l showing the valve and the pistonin another position.

Referring to the drawings, the tool comprises a cylinder A having a boreB in which is arranged a reciprocatory hammer Apiston r C provided inthis instance with a neck C near its forward end. A free exhaust port Dis formed in the cylinder A for exhausting pressure fluid from the frontend of the cylinder and is controlled only by the pis- 30 ton C.

A closure for the front end of the cylinder A is provided in the form ofa front cylinder washer E which projects partly into the cylinder andhas a bore F to receive slidaloly an anvil block G adapted to transmitthe blows of the hammer piston C to a drill steel 'H supported by a.front headL J. A plate K interposed between the front cylinder washer Eand the front head J acts as a closure tor the front end of the bore Fand is bored to receive slidably the front end of the anvil block G. Theforward portion of the bore F is in this instanceV enlarged somewhat toaccommodate a head L carried by the. anvil block G intermediate itsends.

The rearward end of the cylinder bore B is closed by a plate O whichalso serves as a seat for a valve chest P in this instance arranged atthe rearward end of the cylinder. 50 Tn accordance with the presentinvention the valve chest P is provided with a longitudinal chamber Q,having an enlarged portion R' at its forward end.

l/ithin the chamber Q is arranged a dilerential type distributing valveS having 5, 1926. serial No. 146,394. f

an enlarged head rT which extends into the enlarged .portion ROI' thechamber Q and has front and rearward actuating surfaces T `and T2respectively. In the rearward portion ofthevalve S is a recess U whichis in constant communication with the atmosphere tl'irough an exhaustpassage V in the Yvalve chest P. l Y

A plurality of` ports YVV are formed through the valve S, preferablynear the rearward endthereof, and are adapted to registerwvith a supplypassage X leading through the valve chest, the plate O and the wall oithe cylinder A-to the front end of the cylinder bore B. Radial ports Yleading from the .forward end of the recess U through theenlarged head Tare adapted to register with a supply passa-ge Z leading from the valvechamber to the rearward end of the cylinder bore B for exhaustingpressure fluid 'trom tl'ierearward end ot the cylinder A@ I Y Y f fSuitable'means are provided to utilize a portion of the pressure fluidadmitted to the rearward end of thev cylinder bore B for throwing thevalve rearwardly. To this end a passage'b formed in the cylinder A leadsfrom a point rearwardly of the free exhaust port D to communicatevwithits rearward end with the enlargedportionR of the chamber Q.. Within theenlarged 'head T is formed an expansion chamber o andvp'orts fl leadingfrom the expansion chamber c are adapted to communicate with the passageo when the valve is in its forward position to admit pressure fluid intothe said expansion chamber c. The exhaust .of pressure fluid from theexpansionchamber c -is effected through a .passage e leading from thefront end of the :chamber Q to a point in the cylinder Abore Bpreferably in the same transverse plane asythe exhaust Vport D.

The admission of pressure fluid to the drill is effected through aninlet passage f in the valve chest P, leading to a. port g in the valvechamber between the supply passages X and Z.v The means for conveyingpressure fluid from a suitable source of supply to the inlet passage fhave been omit-ted from .the drawings, but it is to be understood thatIUO such means may Yconsist of the usual hose 0r pipes commonly used forthis purpose.

A .small passage 7L in the valve chest P registers at one end with theports el in the head T to establish communication between chamber c andthe passage f for admitting pressure fluid .to the expansion chamber cfor holding the valve after said valve has been thrown rearwardly.

In order to prevent the tool from jumping away from the work upon theadmission of pressure fluid to the front end of the cylinder, a passagey' communicating at its rearward end with the` supply passage X isformed through the front end of the cylinder and through the frontcylinder washer E to communicate with its forward end with the enlargedportion of the bore I?, forwardly of the head Ii of the anvil block. Inthis way, upon the admission of pressure fluid to the front end of thecylinder, a portion of such pressure fluid will pass into the bore F andacting against the head L of the anvil block will hold said anvil blockfirmly against its seat until the free exhaust port D has been uncoveredby the piston C, whereupon the pressure fiuid from the bore F will beexhausted to the atmosphere together with the pressure fluid 'in thefront end of the cylinder,

In the operation of the device, with the valve in the positionillustrated in Figure. l, pressure fluid entering the inlet passage 'fwill pass through the port g and thence through the supply. passage Zinto the rearward .end of ythe cylinder' bore B to drive the piston Cforwardly to deliver its blow. on the anvil block G. After the piston Cuncovers the passage b, pressure fluid will flow from the rearward endof the bore B through said `passage b and through the ports Z in thevalve head T and throw the valve rearwardly. y

IVith the valve in this position, the ports Z will be moved intoregistry with the small passage 7L so that pressure fluid will flowdirectly from the inlet passage into the expansion chamber c for holdingthe valve S in thrown position. Such pressure fiuid admitted into theexpansion chamber' c will then remain therein to hold the valverearwardly7 until the piston C has returned rearwardly a suiiicientdistance to enable the neck C to establish communication between theexhaust passage e and the exhaust port d, whereupon the pressure fluidin the expansion chamber c will be exhausted to atmosphere through thechannels described. After the pressure the expansion fluidin theexpansion chamber c has been thus exhausted, the live pressure fluidacting against the rearward actuating face T2 will throw the valve Sforwardly to again ladmit pressure fluid through the supply passage Z`into the rearward end of the cylinderbore B.

With the valve in its rearward position, the radial ports Yin the head Twill register with the supply passage Z and the pressure fluid in therearward end of the bore B will then be exhausted through these channelsand ,through the recess Il in the valve and the passage V to theatmosphere. Similarly, after the valve has been thrown forwardly, theports IV in the valvewill be in registry with the front supply passage Xto permit the exhaust of any pressure fiuid or air compressed by thepiston from the front end of the cylinder bore B through the valve andthrough the passage V to the atmosphere. y

I claim: i

A pneumatic tool comprising a cylinder having a free exhaust port forthe front end thereof, a piston in the cylinder controlling the freeexhaust port, said piston having a neck, a valve` chest having avalverchamber, supply passages leading from the valve chamber to theends of the cylinder, a valveV chamber having a recess in constantcommunication with the atmo-sphere, a head on one end of the valvehaving opposed actuating surfaces and an expansion chamber, said headalso having radial ports, the rearward actuating surface beingconstantly exposed to pressure fluid for throwing the valve forwardly,ports in the valve to register with the supply passages for exhaustingpressure fluid from the ends of the cylinder into the recess, a kickerpassage leading from the cylinder and adapted to register with t-helports in the head for admitting pressure fluid to the expansion chamberto throw the valverearwardly, and an exhaust passage leading from thefront end of the valve chamber. to a point in the cylinder in the sametransverse plane as the free exhaust port, communication between theexhaust passage and the free .exhaust port being controlled by the neckof the piston.

In testimony whereof I have signed this specification.

WILLIAM A. SMITH, JR.'

